Sensors are being used in a wide variety of automotive electronics applications. The performance of automobile engines, and in many instances the operability and performance of automobile safety systems, depends on sensors. When failures occur, such as open circuits to the sensor power supply, the controlling module cannot operate in accordance with the fault unless the open circuit has been detected. Currently, there is not an easy and cost-effective way to detect the presence of a fault such as, for example, an open circuit to the sensor.
A number of ways exist in the prior art to determine an open circuit in the sensor power supply. For example, one prior art approach is to place a current sense resistor in series with the load (i.e., the sensor) and measure the voltage drop across the resistor. This approach is both burdensome and expensive, in that an operational amplifier and a sense resistor are required. Moreover, power dissipation of the resistor can be very large if a short to ground exists.
Another prior approach to assessing the condition of the sensor circuit has been to remove power from the sensor supply and monitor the decay of the output of the sensor. Such an approach needs to look at the output of the sensor supply and thus requires permanent external circuitry which may ultimately affect the output performance.
Accordingly, there is a continuing need for improved approaches for determining the presence of an open circuit to electronic components such as sensors.